What Can You Safely Add to Hot Tub Water?
Very little, and that is the point. The only things that belong in hot tub water are the treatments the tub is designed around: balancers, a sanitizer, and where used a filter cleanser or a plant-derived stabilizer. Almost everything people are tempted to add, bath salts, essential oils, bubble bath, fragrance crystals, fruit, wine, will shorten the fill, unbalance the sanitizer, foam, or leave residue on surfaces and equipment, and most of it voids a warranty. What people actually want from those additions, scent and a sense of occasion, is available at the water's edge without putting anything in the water.
Not sure where your water is? Check your readings.
What goes in
- Balancers. Products to raise or lower alkalinity, pH and calcium hardness, added one at a time, dissolved in a bucket of tub water first, in the order alkalinity, pH, hardness.
- Sanitizer. Bromine or chlorine, depending on what the tub is made of, held at the working range. Bromine vs chlorine covers which.
- An enzyme or plant-derived stabilizer, where the routine includes one, to reduce organic load between changes.
- A non-chlorine oxidizer after heavy use, timed around the sanitizer, on tubs that use one.
- A metal sequestrant or scale control where the source water calls for it, checked for compatibility with the tub's interior first.
That is the list. Anything not on it is a question, and the safe answer to most questions is no.
What stays out, and why
| Tempting addition | What it does in a hot tub |
|---|---|
| Epsom salt, bath salts | Raises dissolved solids, foams, corrodes metal parts, unbalances sanitizer. More here |
| Essential oils, bath oils | Float, coat the waterline and filter, feed bacteria, cause foam |
| Bubble bath, soap | Foam that will not clear, residue in the filter |
| Fragrance crystals | Usually salt with scent; same problems at a smaller scale |
| Fruit, herbs, flowers in the water | Organic load, staining, sanitizer consumed |
| Wine, beer, drinks | Sugar and organics; cloudy water within hours |
| Household cleaners, vinegar, bleach | Wrong chemistry entirely, and damaging to several tub materials |
| Pool products not labelled for hot tubs | Wrong concentrations, and often incompatible with the tub's interior |
Aromatherapy the right way
Scent shifts a soak more than almost anything, and it does not need to touch the water.
- Beside the tub. A bowl of sliced citrus, crushed rosemary, eucalyptus leaves or cedar sprigs near the water lets the steam carry the scent. Refresh it each session.
- Above the water. A spa-grade aromatherapy mist made for the surface, sprayed over the water before getting in, adds nothing to the chemistry.
- In a muslin bundle hung near the tub, not submerged.
- After the soak, with incense or a warm drink, which is where a lot of the association with scent actually comes from.
One safety line that matters on a wood fired tub: eucalyptus oil and most essential oils are flammable. Keep any oil-based product, including aromatherapy mists, well away from an open firebox and its chimney, and never spray toward the stove. Five rituals to make your outdoor soak more restorative covers scent, light and contrast without additives.
If you have an AlumiTub
The approved list for an aluminum interior is exactly the Good Clean Living Water Care collection plus bromine sourced separately: the Purifier on the fill hose, the Balancers, the Stabilizer monthly, the Filter Cleanser and Booster on tubs with filtration, the Tub Cleanser at each water change, and The (Aroma) Therapist, a eucalyptus mist for the surface rather than the water. Nothing containing chlorine, copper or silver, no salts, no oils, no bath products; damage from unapproved treatments is not covered. On a Wood Fired or Hybrid, keep The (Aroma) Therapist away from the firebox.
Common questions
What can you put in a hot tub for scent?
Nothing in the water. Put scent beside it, a bowl of citrus or crushed herbs that the steam carries, or use a spa-grade aromatherapy mist made for the water surface, which adds nothing to the chemistry. Keep oil-based products away from a wood fired tub's firebox.
Can you put essential oils in a hot tub?
No. Oils float, coat the waterline and filter, feed bacteria and cause foam, and they void most warranties. Use them beside the tub or as a surface mist made for spas, and keep them away from any open flame.
What can you safely add to hot tub water?
Balancers for alkalinity, pH and calcium hardness, a sanitizer at the working range, and where the routine uses them a stabilizer, an oxidizer or a sequestrant, all checked for compatibility with the tub's interior. Anything else is a question, and the safe answer to most is no.
Is aromatherapy oil safe near a wood fired hot tub?
Not near the firebox. Eucalyptus and most essential oils are flammable. Keep oil-based products and mists well away from the stove and chimney, never spray toward them, and use scent beside the tub instead.
Not sure where your water is? Check your readings.